Titanium aluminide alloys, particularly gamma titanium aluminide (TiAl) based alloys, possess a low density combined with high strength and are resistant to oxidation. Gamma titanium aluminide alloys offer a 200.degree. C. temperature advantage over conventional titanium alloys for use as, for example, compressor discs and blades in aero-engines and are only about 50% of the density of nickel-based superalloys. Many aerospace and automobile engine components operate at high temperatures and so a measurement of the strength of the alloy at room temperature, although important, may not be the best indication of how a component will perform at its operating temperature. A more useful test involves loading the alloy at an elevated temperature and observing its creep rate. In particular, the secondary (steady-state) creep rate is an important guide as to how the alloy will perform at elevated temperatures. In addition, the alloy should not be too brittle at room temperature in order to reduce the possibility of fracture.